well, the Japanese school system enforces 1945 kanji for every day use, or "jouyou kanji".
however, not all of these are popular nowdays (but don't shun all of them, I guess only about 20-100 are unpopular, and you will hardly ever see, but don't take my word for it), so the Japanese government takes a record of the 2501 most common kanji used in today's age.
Finally, there's the JTLP Kanji, these are the kanji you will be tested on, for your knowledge of Japanese vocabulary.
Note, I would memorize all three systems, for they will prove useful. I will post good sites for you, and all who wish to use of this.
Jouyou Kanji site- http://www.asahi-net.or.jp/~ik2r-myr/kanji/kanji1a.htm
these notecards are an excellent way to set up your kanji cards, but I would set it up like the white rabbit press cards (http://www.whiterabbitpress.com/catalog/index.html just use the free download to set it up like it. Replace the number you see with the 2051 most commonly used kanji, this site is useful to find it http://www.csse.monash.edu.au/~jwb/cgi-bin/wwwjdic.cgi?1C
note the hand-written kanji link on the bottom, it will prove very useful.)
2051 most commonly used kanji- http://www.hellodamage.com/tdr/archive/7diary/byfreq.html
and finally, the JLTP kanji- http://yosida.com/en/kanji.html
notice, it's divided into 4 levels, level 4 is the easiest and simpler, while level 1 is the hard and complicated kanji (I think they teach that in high-school)
so, I hope this guide was useful, and informative (apologies for it's length) (hopefully, you will notice that the three overlap alot, so don't go making about 6000 notecards, while 3000 of the notecards have the same kanji to eachother (you will need about 3000 notecards)).